1. Field of the Invention
The present invention relates to a weather strip having one or more corners, and including a trim with a seal lip extending from the trim which is expanded when the trim is bent in a curved shape. The weather strip of the invention can be used as a weather strip for various purposes, particularly, as an automotive weather strip for a trunk, a quarter window, or an opening trim.
2. Description of the Related Art
Conventionally, when forming a weather strip having a trim and a seal lip extending from the trim, a U-shaped cut is formed in the seal lip across the edge of the same at a portion corresponding to a portion of the trim to be bent in a curve to form a corner, the weather strip is placed in a mold with the trim bent in a desired curved shape thereby expanding the U-shaped cut, and a corner seal lip is formed in the expanded cut, integrally with the seal lip, by molding. See, for example, Japanese Unexamined Patent Publication (Kokai) Nos. 63-290714 and 59-77939.
FIG. 1A and 1B show a weather strip for a luggage compartment, formed by the above-described conventional technique. This weather strip has a trim 2, integrally provided with an insert 8, a hollow lip 32 which a trunk lid contacts, and a seal lip 4 extending from the lower edge of the outer wall of the trim 2. The weather strip is formed by extrusion. A corner seal lip 63 is formed integrally with the seal lip 4 in a corner of the same. The corner seal lip 63 is formed by forming a U-shaped cut 53 having a fixed length L from the edge 41 of the seal lip 4 to the base side 42 thereof at a portion of the seal lip 4 corresponding to the corner, setting the weather strip in a mold with a portion thereof bent in a desired shape to expand the cut 53, and forming the corner seal lip 63 in the expanded cut 53, integrally with the seal lip 4, by molding.
The material for forming a weather strip having small holding lips 9 within the trim by extrusion, in general, must have a relatively high hardness in view of the necessary hardness of the holding lips and the fitting stability of the weather strip. On the contrary, the material for forming such a weather strip by molding must have a comparatively low hardness in view of the run of the material in the cavity of a mold having a complex shape. Accordingly, the hardness of a solid rubber formed by molding is typically less than that of a solid rubber formed by extrusion; that is, the solid rubber formed by molding is usually softer than the solid rubber formed by extrusion.
When the corner seal lip 63 is formed in the expanded cut of the seal lip with the weather strip bent as shown in FIG. 1A, the restoring force of the trim indicated by arrows F1 compresses the corner seal lip 63 because corner seal lip 63 is formed of a material softer than the material used for forming the extruded portion. Consequently, the weather strip tends to return to its initial shape, namely, the shape before the formation of the corner seal lip 63, and the radius of curvature of the corner increases with time. Eventually, the edge of the corner seal lip 63, particularly, portions of the edge contiguous with the extruded portions are crimped as shown at 10. The shape of the weather strip stabilizes after the curvature of the corner has decreased to some extent.
When setting the weather strip on the body of an automobile, the corner of the weather strip is bent again in the shape formed in the mold, but the crimps 10 are set in permanent strains while the weather strip is kept in stock, so that the permanently crimped portion of the seal lip corresponding to the corner of the weather strip does not exactly conform to the shape of corresponding surface of the body.